//https://leetcode.cn/problems/que-shi-de-shu-zi-lcof/

class Solution {
public:
    int takeAttendance(vector<int>& records) {
        int left = 0, right = records.size() - 1;
        int mid = 0;
        while (left < right)
        {
            mid = left + (right - left) / 2;
            if (records[mid] == mid) left = mid + 1;
            else right = mid;
        }

        return records[left] == left ? left + 1 : left;

    }
};